Federal food officials are warning Americans not to eat any food containing pistachios because of possible contamination by salmonella, in another food scare sure to rattle consumers already upset by the contamination of peanuts with the same bacteria.

The Food and Drug Administration said central California-based Setton Pistachio of Terra Bella Inc., the second-largest U.S. pistachio processor, was voluntarily recalling more than 2 million pounds of its roasted nuts shipped since last fall.

Pistachios Recalled (RAW)

"Our advice to consumers is that they avoid eating pistachio products, and that they hold onto those products," said Dr. David Acheson, assistant commissioner for food safety. "The number of products that are going to be recalled over the coming days will grow, simply because these pistachio nuts have then been repackaged into consumer-level containers."

Two people called the FDA complaining of gastrointestinal illness that could be associated with the nuts, but the link hasn't been confirmed, Acheson said. Still, the plant decided to shut down late last week, officials said.

Meanwhile, it has emerged that the salmonella scare may have erupted because contaminated raw nuts got mixed with roasted nuts during processing, the company at the center of the nationwide recall said Tuesday.

Lee Cohen, the production manager for Setton International Foods Inc., said the company does not believe pistachios were contaminated by a human or animal source in its plant. He said the company suspects that roasted pistachios sold to Kraft Foods Inc. may have become mixed at Setton's plant with raw nuts that could have contained traces of the bacteria.

The pistachios were processed at central California-based Setton Pistachio of Terra Bella Inc., which is in the corporate family of Commack, N.Y.-based Setton International Foods Inc. Cohen is in California to help as the FDA inspects the nation's second-largest pistachio processor.

Kraft spokeswoman Laurie Guzzinati said her company's auditors "observed employee practices where raw and roasted nuts were not adequately segregated and that could explain the sporadic contamination."

She said she didn't know what they saw specifically, but "that's how the auditors shared the information with us."

The recalled nuts are a small fraction of the 55 million pounds of pistachios that the company's plant processed last year and an even smaller portion of the 278 million pounds produced in the state in the 2008 season, according to the Fresno-based Administrative Committee for Pistachios.

California is the second-largest producer of pistachios in the world.

The FDA learned about the problem last Tuesday, when Kraft Foods Inc. notified the agency that routine product testing had detected salmonella in roasted pistachios. Kraft and the Georgia Nut Co. recalled their Back to Nature Nantucket Blend trail mix the next day.

The FDA contacted Setton Pistachio and California health officials shortly afterward, in what Acheson called a "proactive move."

By Friday, Cincinnati-based grocery operator Kroger Co. recalled one of its lines of bagged pistachios because of possible salmonella contamination, saying the California plant also supplied its nuts. Those nuts were sold in 31 states.

Fabia D'Arienzo, a spokeswoman for Tulare County-based Setton Pistachio, said the company was only recalling certain bulk roasted in-shell and roasted shelled pistachios that were shipped on or after September 1.

Because Setton Pistachio shipped bags of nuts weighing up to 2,000 pounds to 36 wholesalers across the U.S., it will take weeks to figure out how many products could be affected, said Jeff Farrar, chief of the Food and Drug Branch of the California Department of Public Health.

"It will be safe to assume based on the volume that this will be an ingredient in a lot of different products, and that may possibly include things like ice cream and cake mixes," Farrar said. "The firm is already turning around trucks in transit to bring those back to the facility."

Salmonella, the most common cause of food-borne illness, causes diarrhea, fever and cramping. Most people recover, but the infection can be life-threatening for children, the elderly and people with weakened immune systems.

Roasting is supposed to kill the bacteria in nuts. But problems can occur if the roasting is not done correctly or if roasted nuts are re-contaminated. That can happen if mice, rats or birds get into the facility.

The national peanut salmonella outbreak was blamed on a Georgia company under federal investigation for flouting safety procedures and knowingly shipping contaminated peanuts.

That outbreak is still ongoing and is not related to the pistachio scare. More than 690 people in 46 states have gotten sick. Nearly 3,900 products made with peanut ingredients from Peanut Corp. of America have been recalled.

California public health authorities have taken hundreds of samples at Setton's processing facility, but lab results have not yet determined whether salmonella was found at the plant, Farrar said. The food companies' own tests of the contaminated products isolated four different types of salmonella, but none were the same strain as the one found in the peanuts, Acheson said.